In response to recent demands for a high-speed semiconductor device, fine wiring pattern, and high-integration, it has been necessary to decrease the capacity between the wirings, improve the conductivity of the wiring, and improve the electromigration resistance. In this respect, the Copper (Cu) multilayer wiring technology comes into the spotlight. In this technology, Copper with conductivity and electromigration resistance values higher than those of Aluminum (Al) or Tungsten (W) is used for a wiring material, and a low-k dielectric film is used for an interlayer insulating film. A low-k dielectric film having the alkyl group, such as the methyl group, as the end group is generally used, and a damascene process such as the dual damascene method is widely used for forming an wiring groove or a contact hole.
In the damascene process, the interlayer insulating film made of the low-k material is damaged in etching or removing the resist film, which causes the increase of the dielectric constant of the interlayer insulating film and thus deteriorates the effect of using the low-k material. Therefore, as for the technology of repairing the damage, performing a silylation treatment after etching or removing the resist film has been suggested. For example, a conventional silylation treatment is disclosed in Japanese Laid-open Patent Publication No. 2006-49798.
The silylation treatment is implemented by a silylation unit that gasifies liquid silylating agents at an indoor temperature to supply the gasified silylating agents into a chamber, and makes the inside of the chamber be a predetermined gas atmosphere. Further, the damaged portion of the low-k dielectric film formed on the target substrate is reformed through the silylation treatment to have the alkyl group, such as the methyl group, as the end group.
In the silylation unit, the flow quantity of the liquid silylating agents is controlled by a mass flowmeter to supply a certain quantity of the liquid silylating agents into an evaporator to heat the evaporator, and the silylating agents gasified in the evaporator are supplied into the vacuum-maintained chamber. As the inside of the chamber is vacuum pressurized, the silylating agents supplied into the chamber is completely gasified, and the exhaustion valve is closed so that the gas pressure in the chamber gradually increases. Further, the valve supplying the silylating agents is closed when the pressure within the chamber increases to the treatment pressure, and the inside of the chamber is filled with the gas-state silylating agents atmosphere that is maintained with the treatment pressure for a predetermined amount of time, so as to cause a silylation reaction.
However, in order to prevent dew condensation, the conventional silylation unit cannot raise the temperature of the evaporator so high, and there exists a liquid residual in the pipe, or the like. Further, the flow quantity of the silylating agents is controlled in the liquid state and therefore, the silylating agents are excessively supplied during the period from transmitting the valve-closing signal to actually closing the valve. Due to this, the conventional silylation unit causes the substantial quantity of the useless silylating agents to remain.
Further, the evaporator or mass flowmeter used in the conventional silylation unit is expensive and the cost of the apparatus is high.
Furthermore, such problems are not limited to the silylation unit, but can be generally incurred in the gas treatment apparatus which gasifies the liquid material by means of the evaporator to supply the gasified material into the chamber and makes the inside of the chamber be a gas atmosphere to treat the target substrate using gas.